1. Field of the Invention
The present invention relates to an information record medium such as an optical disk of a high recording density type, which is capable of recording information such as video information, audio information and the like at a high density, and which is represented by a DVD (Digital Video or Versatile Disk). The present invention also relates to a recording apparatus for recording the information onto the information record medium, and a reproducing apparatus for reproducing the information from the information record medium.
2. Description of the Related Art
Conventionally, a so-called LD (Laser Disk) and a so called CD (Compact Disk) are generalized as optical disks, on which information such as video information, audio information and the like is recorded.
On the LD, the CD or the like, the video information and the audio information are recorded together with time information indicating a time at which each information is to be reproduced with respect to a reproduction start position, which each LD or the like has, as a standard position. Thus, other than a general normal reproduction to reproduce the recorded information in the order of recording, various special reproductions are possible, such as a reproduction to extract and listen to an only desirable music out of a plurality of recorded musics, a reproduction to listen to the recorded musics in a random order and so on, in case of the CD, for example.
However, there is a problem that, according to the above mentioned CD, LD or the like, a so called interactive and variegated reproduction is not possible in which the audience can have a plurality of selection branches as for the video or audio information to be displayed or sound-outputted and in which the audience can select them to watch or listen to it.
Namely, for example, in case of giving audience to a foreign movie on the LD, it is not possible to select one of languages to be used for a subtitle (caption) displayed on the picture plane (e.g. select one of the subtitle in Japanese and the subtitle in the original language) so as to display the subtitle in the selected language, or, in case of giving audience to a music recorded on the CD, it is not possible to select one of sound voices of the music (e.g. select one of the English lyric and the Japanese lyric).
On the other hand, various proposals and developments are being made as for the DVD, as an optical disk in which the memory capacity is improved by about ten times without changing the size of the optical disk itself as compared with the aforementioned conventional CD. According to the knowledge of the present inventors, it is anticipated that it is possible, as for the DVD having such a large memory capacity, to: divide audio information, video information or the like by an appropriate length respectively into an audio pack, a video pack or the like; add additional information such as header information to each pack; switch and multiplex these packs; and reproduced the multiplexed audio information, video information or the like.
However, in the field of the audio or video related technique, the audio information, the video information or the like is generally treated in a relatively large unit e.g. a so called audio frame or video frame, at the time of recording, editing and reproducing by the recording apparatus and the reproducing apparatus. Thus, for example, assuming that the frequency of this audio frame is 75 Hz, which is the same as the case of CD, the compatibility in frequency of the audio frame is generally bad with the audio pack, the video pack or the like multiplexed in the aforementioned DVD. This results in that a very complicated reproduction method is estimated to be necessary. Further, in the technical art of the DVD, the actuality is such that a person having an ordinary skill in this art does not even recognize the subject or problem itself that the compatibility in frequency of the audio frame used in the conventional CD etc. is bad with the audio pack etc. which is expected to be usable in the aforementioned DVD,